The present disclosure relates to a power conversion device such as an AC/DC power supply.
In order to reduce power consumption of electronic equipment, there is a need to increase the efficiency of power conversion devices such as power supplies. For example, in a so-called “AC/DC power supply” configured to convert AC power to DC power, power conversion is performed in such a manner that AC power is converted into DC power in a diode rectifier and then the DC power is converted into desired voltage in a DC/DC converter. However, since a power conversion loss is caused in the diode rectifier and the DC/DC converter, it is important for higher efficiency of the power supply to reduce the power conversion loss in the diode rectifier and the DC/DC converter.
A diode rectifier-less power supply including a bidirectional switch has been proposed as a circuit configured to reduce a loss caused in a diode rectifier (see Japanese Unexamined Patent Publication No. 2007-028894). The loss caused in the diode rectifier has been eliminated, and the efficiency of an AC/DC power supply can be increased. However, since a normally-on bidirectional switch causing current to flow at a gate voltage of 0 V is used, there is a possibility that current cannot be interrupted at an abnormal state of a gate circuit and therefore a power supply circuit is damaged.
On the other hand, a normally-off bidirectional switch capable of interrupting current at a gate voltage of 0 V has been known (see International Patent Publication No. WO 2008/062800 and Japanese Unexamined Patent Publication No. 2009-148106).